Apparatus and method for detecting and removing moisture and contaminants in a fuel storage tank

ABSTRACT

An apparatus for detecting and removing moisture and contaminants from fuel stored in a tank includes optical fiber for examining the fuel for moisture and contaminants, a light source and a lens; a suction and return hoses insertable into the tank; a pump connected to the suction hose, a waste holding container for receiving moisture and contaminants; a contaminant filter connected to the return hose; and a valve between the pump outlet, the waste holding container and the contaminant filter inlet.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of application Ser. No. 11/105,792 filed Apr. 14,2005, now U.S. Pat. No. 7,473,352 issued Jan. 6, 2009.

BACKGROUND OF THE INVENTION

The present application relates to an apparatus and method for removingwater and other contaminants from fuel, and particularly to the use ofan fiber optic cable and lens for viewing the presence of such water andcontaminants.

Operation and maintenance have quickly become the new buzzwords inregulatory circles. Ask any inspector about underground storage tankcompliance issues and the inspector will quickly cite leak detection,cathodic protection testing, piping, sumps and under-dispenser boxes asprimary concerns. Water has this nasty habit of getting into placeswhere it does not belong. This includes sumps, dispenser boxes,basements and even tanks. Water can enter tanks by way of theinfrastructure, which includes pipelines, barges or trucks. But it canalso enter an underground storage tank (UST) or above ground storagetank (AST) by condensation, Fill boxes or tank sumps. Of course, a tankat a retail service station is the last place an owner-operator wants tofind water. That water needs to be removed before it gets sucked into amotor vehicle's fuel tank, which can lead to irate motorists.

A number of organizations have developed recommended practices andstandards to monitor water in tanks and provide for its removal. Beforethe days of automatic electronic liquid sensing and inventory devices,some operators daily used a special paste on a gauge stick to determineif water had entered the tank. American Petroleum Institute includedprocedures within their recommended practices with the goal to minimizethe water content and maximize fuel quality. See API 1621, “Bulk LiquidStock Control at RetailStations,” and API 2610, “Design, Construction,Operation, Maintenance, and Inspection of Terminal & Tank Facilities.”Steel Tank Institute recommends that water be removed from steel storagetanks on a regular basis within their tank installation and maintenancepractices. Petroleum Equipment Institute's RP 100-2000, “RecommendedPractices for Installation of Underground LiquidStorage Systems,”states, “Install tanks to facilitate water removal.”

For example, a tank can be sloped so that water collects at one end foreasier removal. By removing the water, the life of the fuel filter andother dispensing-system components will be extended. More importantly,the gas-buying customer is assured of a quality fuel product. Thequestion of how to address water in UST and AST systems has taken onadded urgency during the last two decades as America's quest for cleanerair has led to new fuel blends featuring oxygenates. California is thelargest state to ban the oxygenate MTBE. Major oil companies inCalifornia have already begun using ethanol and taken the necessarysteps with their UST systems to ensure a smooth transition. With thereplacement of MTBE by ethanol throughout America likely to take placeduring the next few years, the need to keep water out of tanks is aneven more important task than ever before, as ethanol blends are verysensitive to water. (See www.steeltank.com for more on ethanol-blendedfuels.) The operation and maintenance issues reach critical mass whenethanol combines with water and microscopic matter. Variousmicroorganisms are carried in air and water.

Tanks with poor housekeeping are likely to see a buildup of sludge inconjunction with the water. The sludge serves as a breeding ground asthe microorganisms multiply and form a potentially hazardous microbialcolony, regardless of the type of tank material storing the fuel.Filters can be clogged frequently, product flow to the vehicle slowsdown, and the quality of fuel diminishes when such microbes begin tofeed and grow in the water layer trapped at the tank bottom. In the caseof steel, the microbes, or bugs, can create a corrosive environment. Inplastic tanks where a high alcohol content has led to phase separationat the tank bottom, the plastic is subject to softening and canexperience a reduction in its strength properties.

There is a need for an improved apparatus and method to remove water andother contaminants from fuel in fuel storage tanks.

SUMMARY OF THE INVENTION

An apparatus for detecting and removing moisture and contaminants fromfuel stored in a tank, the apparatus comprising:

(a) optical fiber for examining the fuel for moisture and contaminants,further comprising a light source and a lens;

(b) a suction hose insertable into the tank.

(c) a return hose insertable into the tank;

(d) a pump having an inlet connected to the suction hose, the pump alsohaving an outlet;

(e) a waste holding container for receiving moisture and contaminants;

(f) a contaminant filter having an inlet and an outlet, the outletconnected to the return hose; and

(g) a valve between the pump outlet, the waste holding container and thecontaminant filter inlet.

A method for detecting and removing moisture and contaminants from fuelstored in a tank, comprising the steps of:

(a) optically inspecting fuel in the tank for moisture and contaminants;

(b) pumping fuel laden with moisture and contaminants into a measuringcontainer until the measuring container is full;

(c) pumping the contents of the measuring container into a holdingcontainer;

(d) examining the fuel to determine whether the fuel is substantiallyclean of moisture and contaminants, returning to step (b) until the fuelis substantially clean of moisture and contaminants;

(e) pumping the fuel from the tank through a contaminant filter and thenback into the tank until the fuel is free of moisture and contaminants;and

(f) terminating pumping.

A principal object and advantage of the present invention is thatmoisture and contaminants in a fuel tank can be accurately detected atany location in the tank.

Another principal object and advantage of the present invention is thatthe amount of contaminated fuel removed can be accurately measured.

Another principal object and advantage of the present invention is thatit is not necessary to remove all fuel from the tank in order to rid thefuel of moisture and contaminants.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of the environment of the present invention.

FIG. 2 is a block diagram of the present invention.

FIG. 3 is a schematic cross-section taken at approximately the lines 3of FIG. 2.

FIG. 4 is a block diagram of a second embodiment of the presentinvention.

FIG. 5 is a flowchart of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The environment in which the present invention operates and to which theobjects and advantages of the present invention apply is shown inFIG. 1. A fuel storage tank T may be either above ground or underground(an underground tank is shown in the Figure). The tank T has a pump Pfor pumping fuel out of the tank to a fuel dispenser D. A fill pipe FPis used to add fuel to the tank T, for example but not exclusively, froma vehicle V. An inspection port I allows access to the tank forinspection of the tank and its contents. Fuel F is stored in the tank T.Moisture M, such as liquid water, and other contaminants C may also bepresent in the tank.

Typically, the fuel F will be on top of the moisture M because of therelative specific gravities. Contaminants C may either be in themoisture M or suspended in the fuel F.

The present invention is shown in the Figures as reference numeral 10.

FIG. 2 is a block diagram of one aspect of the present invention at ahigh level. As shown in FIG. 2, the present invention is an apparatus 10for detecting and removing moisture and contaminants from fuel stored ina tank, the apparatus 10 comprising an optical fiber 20 for examiningthe fuel for moisture and contaminants, a light source 22 connected tothe optical fiber 20, and a lens 24 connected to the optical fiber 20. Asuction hose 30 is insertable into the tank T, typically through theinspection port I. A return hose 32 is also insertable into the tank T.A pump 40 has an inlet 42 connected to the suction hose 30, and outlet44. A waste holding container 50 receives moisture and contaminants fromthe tank T through the suction hose-30 and pump 40. A contaminant filter60 having an inlet 62 and outlet 64 is connected to the return hose 32at the outlet 64. A valve 70 connects the pump outlet 44 to either thewaste holding container 50 or to the contaminant filter inlet 62.

Because of the presence of fuel vapors in the environment, the pump 40cannot be electrically driven. Preferably, the pump 40 is driven by anair compressor 80. Suitably, the pump 40 may be a diaphragm or membranepump. The air compressor 80 is connected to the pump 40 through airlines 82, 84.

Preferably, the suction hose 30, return hose 32, and optical fiber 20are carried to the tank T as a unit, typically within a common carrier100, a illustrated in FIG. 3. The common carrier may be a spring 102enclosing the hoses 30, 32 and the fiber 20.

Preferably, the apparatus 10 further comprises a directional probe 110attached to the optical fiber 20, to the suction hose 30, and to thereturn hose 32.

FIG. 4 is a schematic of a second and preferred embodiment of thepresent invention.

The second embodiment is similar to the first embodiment with theaddition of a waste measuring container 120 and appropriate valving. Ashut-off valve 122 is placed between the pump outlet 44 and the wasteholding container 50. A selector valve 124 is used to direct fluid fromthe pump outlet to either the waste measuring container 120 or to thecontaminant filter inlet 62. Additional suction hoses 30 may be added asnecessary to increase volume or to reach other portions of the tank.Additional valves 37 may be provided to choose which suction hose 30 isto be active. Additional waste containers 50 may also be added withsuitable valves 52. A valve 126 may be placed between the wastemeasuring container 120 and the pump inlet 42 to allow fluid in thewaste measuring container to be removed. Valves 128 may be added toconnect the waste holding container 50 to the pump 40 and thus to pumpthe contents of the waste holding container 50 into a waste storagecontainer (not shown). A panel 140 may be provided to house the lens 24and various valves.

The apparatus 10 may be mounted on a vehicle 150 for transport. Ifnecessary, the air compressor 80 may be mounted on a separate vehicle160.

In either embodiment, a gravel filter 36 may be placed between thesuction hose 30 and the pump inlet 42 to prevent gravel from the tank Tentering the pump 40.

Detailed operation of the second embodiment will now be described.Operation of the first embodiment is simpler and may be easilyunderstood without further description.

The tank inspection port I is opened. The directional probe 110 isinserted into the tank until it contacts the fuel F. The operator mayrotate the directional probe 110 to view different parts of the tankusing the lens 24, with the light source 22 illuminating the fuel. Whenmoisture (typically liquid water) and/or contaminants (such as bacteriaor rust) are encountered, the selector valve 124 is set to move liquidthrough the suction line 30, the pump 40, and the pump outlet 44 to thewaste measuring container 120. Shut-off valve 122 is set to preventliquid from flowing to the waste holding container 50. When the wastemeasuring container 120 fills to an operator-determined point, valves126 and 122 are opened to pump the contents of the waste measuringcontainer into the waste holding tank 50. When most of the moisture andcontaminant has been removed from the fuel, the valve 124 is set todirect the output of the pump 40 to the contaminant filter 60, andfiltered fuel is returned to the tank T. After a suitable time, theapparatus is shut down.

By the above operation, only the waste (water and contaminants) areremoved from the tank, not good fuel.

FIG. 5 is a flowchart of the method of the present invention.

In a second aspect, the invention is a method for detecting and removingmoisture and contaminants from fuel stored in a tank, comprising thesteps of:

200: Optically inspecting fuel in the tank for moisture andcontaminants.

210, 215: Pumping moisture and contaminants into a measuring containeruntil the measuring container is full.

220: Pumping the contents of the measuring container into a holdingcontainer.

230: Examining the fuel to determine whether the fuel is substantiallyclean of moisture and contaminants, returning to step 210 until the fuelis substantially clean of moisture and contaminants.

240, 245: Pumping the fuel from the tank through a contaminant filterand then back into the tank until the fuel is free of moisture andcontaminants.

250: Terminating pumping.

Steps 230 and 245 may be performed in any manner that allows the fuel tobe tested for the presence of moisture and contaminants. For example,the contents of the measuring container may be visually inspected.Alternatively, chemical testing may be performed on the fuel. Theimportance of the process is that it is not necessary to remove all fuelfrom the tank to remove the moisture and contaminants, but rather toremove only contaminated fuel.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar to or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety to the extent allowed by applicable law andregulations. In case of conflict, the present specification, includingdefinitions, will control.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof, and it istherefore desired that the present embodiment be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than to the foregoing description to indicatethe scope of the invention.

1. A method for detecting and removing moisture and contaminants fromfuel stored in a tank, comprising the steps of: (a) optically inspectingfuel in the tank for moisture and contaminants; (b) pumping fuel ladenwith moisture and contaminants into a measuring container until themeasuring container is full; (c) pumping the contents of the measuringcontainer into a holding container; (d) examining the fuel to determinewhether the fuel is substantially clean of moisture and contaminants,returning to step (b) until the fuel is substantially clean of moistureand contaminants; (e) pumping the fuel from the tank through acontaminant filter and then back into the tank until the fuel is free ofmoisture and contaminants; and (f) terminating pumping.